Background: Effective teamwork and team performance are critical to error mitigation and safety in the clinical environment. The team science literature identifies three targets for improving team performance: team design (composition), team training, and team leadership. To date, efforts have focused on team training. However, challenges associated with the feasibility, sustainability, and effectiveness of these programs have been identified. Additionally, training teams as a unit, while required for effective training outcomes, is nearly impossible for ad hoc emergency teams characterized by an interdisciplinary, highly variable membership that operates under complex, dynamic and time pressured conditions in a clinical setting. This proposed research focuses on team leadership and team composition as two important mediators of medical emergency team performance that have not been studied in patient safety research. Objective: The overall objective of the proposed research is to (1) develop a novel, evidence-based leadership training program and (2) evaluate the impact of both leadership training and team member composition (unfamiliar vs. familiar teams) on medical emergency team performance using a simulation-based research platform. This will advance the patient safety mission of AHRQ by (1) providing an additional mechanism (leadership training) for improving team performance and patient safety that overcomes challenges associated with current team training programs, (2) providing a robust, diagnostic method of evaluating team performance that directly assesses evidence-based team processes (coordination, back-up behavior, etc), and (3) investigating the impact of team composition on team performance and patient safety critical behaviors. Methods: This project builds upon previous work and is structured into three specific aims: Aim 1: To assess the impact of healthcare team composition (unfamiliar vs. familiar members) on medical emergency team performance Aim 2: To develop and implement a team leadership training program based on an Adaptive Learning System theoretical heuristic Aim 2a: To assess the impact of team leadership training on medical emergency team performance Aim 3: To assess the differential impact of team leadership training on unfamiliar vs. familiar medical emergency teams This project uses a 2 (unfamiliar vs. familiar) X 2 (leadership training vs. control) fully crossed design to evaluate impact of leadership training and team composition (unfamiliar vs. familiar) on ad hoc medical emergency team performance. Ad hoc medical emergency teams will be comprised of emergency medical nurses and physicians from multiple hospital institutions. The primary outcome measure is team performance, assessed using a validated simulation platform (scenario + team process measures + patient care measures). These measures will collectively represent an accurate, reliable representation of both teamwork and taskwork. PUBLIC HEALTH RELEVANCE: The proposed project seeks to improve teamwork in emergency healthcare teams by evaluating the impact of team member familiarity and leadership training on healthcare team performance using simulation-based assessment. Medical emergency teams present significant risks to patient safety due to their inherent design, the nature of their tasks, and the environment in which they function. The evidence-based simulation-based assessment approach used in this research can be applied to address some of the assessment and outcomes challenges reported in the healthcare team literature. Additionally, the leadership-targeted training addresses many of the feasibility and sustainability issues present in large-scale team training programs (e.g., TeamSTEPPS). Finally, the use of theoretically and empirically supported leadership and team processes means this work is compatible and synergistic with currently existing teamwork and patient safety interventions.